As the machinery having the modern linear motion guide units increasingly needs to work over a prolonged service life even under harshest atmosphere in which much foreign material including chips, debris, dirt, dusts, processing fluids and so on occurs, applications of the linear motion guide units grow in recent years to a variety working sites and installation sites. Making sure of operation of the linear motion guide units in the harshest environment is first to keep the interior of the slider free of foreign materials or contaminants. Even with any invasion of outside foreign materials into the slider, the most significant issue is how to protect at least the circulating circuit including the load-carrying races to allow the rolling elements running through there against the foreign materials or contaminants. What's more, many of modern linear motion guide units are customized to have no conventional dustproof means including a telescopic cover, bellows, and so on despite laying their guide rails bare to the severe working atmospheres from the aspect of making the guide units themselves compact in construction, cost savings on installations, and so on while keeping the circulating circuits for the rolling elements free of the foreign material or contaminants.
A linear motion guide unit is disclosed in Japanese Laid-Open Patent Application No. H07-293 561 which is one of the common-assigned JP patent applications. With the prior linear motion guide unit, the upper seal 73 as shown in FIGS. 20 and 21 may be demounted from the slider 70 without removal of the end cap 72 from carriage 71. The upper seal 73 serving as the inside seal in the linear motion guide unit constructed as stated earlier is composed of the metallic core plate 75 whose widthwise opposed side edges have lip seals 74. The upper seal 73 is provided at lengthwise opposite ends thereof with projecting tongues 78. The upper seal 73 is kept inside the grooves 76 after the projecting tongues 78 have been inserted into the slots 79 made in the end caps 72. With the prior linear motion guide unit constructed as stated earlier, as the structure to retain the upper seal 73 is provided between the concaved lower surfaces 80 inside the slider 70 and the top surface 81 of the guide rail 77, the concaved lower surfaces 80 of the slider 70 have to be machined or cut to ensure the space to stow the upper seal 73 and make the grooves 76 to retain the upper seal 73.
Another commonly-assigned Japanese Laid-Open Patent Application No. 2008-281 091 discloses a linear motion guide unit with an inside seal to keep the circulating circuit including the load-carrying races free of any foreign material creeping into a slider even in harshest operating atmosphere in which much foreign material occurs. This prior linear motion guide unit has a lip-type inside seal constructed as stated earlier. The lip-type seal is installed in the linear motion guide unit in a fashion introduced aslant relative to the end caps while getting tongue lugs at opposite ends of the inside seal inserted into the slots in the lower surfaces of the end caps. The structure to retain the inside seal is provided between the lower surface of the slider and the top surface of the guide rail. Thus, it is needed to cut or machine the concaved lower surface of the carriage to ensure the space to stow the upper seal and make the grooves in the end caps to retain the upper seal.
Another commonly-assigned Japanese Laid-Open Utility Model Application No. H06-49 824 discloses a linear motion guide unit with a lower seal. Sidewise opposed bulges of the inverted U-shaped end cap have grooves on their inside surfaces opposing to the guide rail. The lower seal at opposite ends thereof has hooked engaging portions which fit into the grooves to retain the lower seal to the end cap. The lower seal has a metallic core plate which is bent to make the hooked engaging portion to make into engagement with the end cap.
Another commonly-assigned Japanese Laid-Open Patent Application No. H07-71 455 discloses a linear motion guide unit in which a lower seal is installed with the help of the space reserved in the carriage for a grindstone. With the linear motion guide unit constructed as stated earlier, the lower seal is installed in the space for a grindstone reserved on the slant surface lying on the lower surface of the carriage in adjacency to the guide rail. The lower seal at the lengthwise opposite ends thereof has upright brackets with engaging hooks and correspondingly the end caps have mating holes to make engagement with the hooks on the lower seal.
A further another Japanese Laid-Open Patent Application No. 2004-124 957 discloses the linear motion guide unit having sealing members 86 sharing inside seals 87 with lowers seals 88 as shown in FIGS. 22 to 24. The linear motion guide unit is composed of a guide rail 83 and a slider 82 with end lids 91. The slider 82 fits over or conforms to the guide rail 83 for movement in a sliding manner relative to the guide rail 83. The slider 82 has the sealing members 83 serving as both the inside seals 87 and the lower seals 88. The sealing member 86 is composed of a metallic core 89 of substantial L-shape in a transverse section and a lip 90. The sealing member 86 has lengthwise opposite ends 92 bent on opposite side of the lip 90 to provide fastening means. The sealing member 86 is fastened to the concaved surface 84 of the slider 82, facing on the top surface 85 of the guide rail 83. The metallic core 89 on the sealing member 86 is set to protrude from the concaved surface 84 of the slider 82 towards the guide rail 83. Moreover, the metallic core 89 is elastic or resilient to control adequately the frictional resistance of the sealing member 86 against the guide rail 83. The sealing member 86 is beneficial when the concaved surface 84 of the slider 82 is spaced from the top surface 85 of the guide rail 83 across the significant interval. On the contrary, the sealing member 86 constructed as stated earlier couldn't be befitted for the linear motion guide unit in which there is less in spacing interval between the concaved surface 84 of the slider 82 and the top surface 85 of the guide rail 83.
Most inside seals used in the linear motion guide units conventionally have a flat configuration of which widthwise opposite edges have sealing lips. The inside seals at their lengthwise opposite ends have tongue projections to keep the inside seals on the slider and, correspondingly the end caps have sockets designed to fit over the tongue projections of the inside seals to hold the inside seals on the slider. If there is less in spacing interval between the concaved surface of the slider and the top surface of the guide rail, it is needed to cut or machine the groove in the concaved surface to stow the inside seal in the slider. This additional procedure would introduce costly machining requirements Moreover, there is left a clearance between the tongue projections of the inside seal and the sockets of the slider and, therefore, mounting and demounting of the inside seal from the slider may be easily carried out only by unfastening or loosing fastening bolts to dislodge just the inside seal. As a result, there is the possibility the inside seal shifts out of place relative to the slider while the slider moves along the guide rail unless the slider at the opposite ends thereof has the end seals to press down the opposite ends of the inside seal. The inside seal, as suffered to a reaction owing to any interference against the top surface of the guide rail, experiences a reaction caused by frictional resistance encountered on the seal lips and correspondingly the tongue projections on the inside seal are suffered to any load of moment direction. This means that the tongue projections on the inside seal is liable to adversely cause any deformation under either of the reaction owing to any interference of the seal lips and the bending reaction caused by frictional resistance because the inside seal is made of the metallic core of the flat thin configuration.
With prior linear motion guide unit constructed as stated earlier, the seal lip fastened to the foremost end of the inside seal, because of very tiny in size and in adhered area to the inside seal, is easily come off the metallic core of the inside seal owing to the frictional resistance while the slider slides along the guide rail. Moreover, the inside seal needs to precisely control the member for the seal in thickness and contour because the resiliency of the metallic core for the inside seal has a major influence on adjustment of the contact pressure of the seal lip and fastening function of the inside seal to the end cap.